This project provides statistical, operational, and coordinating support for the design, conduct, analyses, and reporting of clinical trials in the therapy of malignant diseases conducted by the Cancer and Leukemia Group B (formerly Acute Leukemia Group B). It services the cooperative research of 450 scientists in over 75 international hospitals and clinical centers. About 10 new investigations are undertaken each year, while an average of 30 studies are accruing nearly 2000 patients with a variety of cancers and leukemias each year. These studies range in character from the investigation of potential therapeutic effects of new chemotherapeutic agents in advanced cancer patients to the systematic search for curative combinations of surgery, radiotherapy, chemotherapy, and immunotherapy in newly diagnosed cancer patients. Uniform data are centrally collected, processed, analysed, and stored from these experiments, and interim results are regularly reported to participating physicians. These data now form a library of nearly 20,000 cancer patients treated in accordance with carefully designed experimentally therapeutic trials over two decades of Group research.